The present invention relates generally to starch hydrolyzate products and to methods for producing such products and more particularly to a method for producing a particulate maltodextrin product which has both a relatively high bulk density and a relatively high solubility in water compared to other maltodextrin products of the same or finer particle size.
Starch hydrolyzate products, such as maltodextrins, are produced by the partial hydrolysis of cereal or root base starches, preferably corn, waxy corn or potato starch. Maltodextrins are commercially available in spray dried, particulate form, and they generally have a relatively low sweetness level, expressed as dextrose equivalent (D.E.), below 20 D.E.. When the D.E. is 20 or above, the starch hydrolyzate product is considered to be a sweetener, and a statement to this effect must be included on the label of any food or the like containing a product having a D.E. of 20 or above. Such foods cannot be characterized as 100% artificially sweetened, a characterization which is oftentimes desireable from a marketing standpoint. Because maltodextrins have a D.E. below 20, they can be used as a bulking agent or carrier for synthetic sweeteners (e.g. aspartame), and the resulting product can be characterized as 100% artificially sweetened.
Other properties of commercially available maltodextrins include a low moisture content, e.g. 4-6%, a bulk density of 0.4-0.7 g/cc, and a relatively fine particle size, e.g. 95% finer than 100 mesh and 50% finer than 200 mesh. (All particle sizes are expressed herein as U.S. Standard mesh).
Conventional commercially available maltodextrins, produced by the partial hydrolysis of starch, are difficult to completely hydrate, i.e. to dissolve in water. Because of the fine particle size, such maltodextrins require high shear mixing and low rates of addition to the water or other dissolution liquid in order to avoid the formation of small agglomerates of maltodextrin particles which are wet on the outside but dry within. The fine particle size also creates dusting and flow problems and static charge problems when high speed packaging equipment is employed to package a product containing such fine particles.
There are procedures for treating maltodextrins to make them hydrate more readily. One such procedure comprises spraying, onto the maltodextrin particles, a 50/50 mixture by weight of alcohol and water (or water alone) while suspending the particles in a fluid-bed granulator/dryer in which the maltodextrin and alcohol/water solution are mixed to form an agglomerate which is granulated, dried and sieved to the desired particle size distribution (e.g. -20 to +80 mesh). The result is a dry, free-flowing granulation with no fines. The agglomerate particles are clusters having spherical and egg-shaped configurations and comprising smaller individual particles loosely held together with a minimum of particle-to-particle contact. The agglomerates or clusters contain numerous voids which can be readily infiltrated by water during hydration, and the voids significantly increase the rate of hydration or solution. A drawback to this treatment is that it reduces the bulk density of the maltodextrin too far below that of the starting product, e.g. to 0.16-0.35 g/cc, which is undesirable for the reason described in the following paragraph.
Certain food products such as artificial/nutritive sweeteners are typically packaged in one gram packets, employing high speed packaging equipment. In such high speed packaging equipment, the agglomerated particles described in the previous paragraph would be susceptible to static charge and, due to their low bulk density, it would become difficult to fill one gram packets on a uniform weight basis with agglomerated particles.
There are procedures for increasing the bulk density of maltodextrin particles, but these procedures have other drawbacks. One such procedure is to compress the agglomerated particles described above into tablets or slugs of increased density which can then be milled and sieved to the desired particle size distribution. The drawbacks of this procedure include the fact that all the voids have been compressed out of the resulting densified particles, thereby forming a solid body which can go into solution only by surface erosion, thus significantly decreasing the rate of solution. In addition, a lubricant is required to separate the tablet from the die cavity in which it was compressed, and this lubricant is typically a hydrophobic powder (e.g. magnesium stearate, calcium stearate, hydrogenated vegetable oils, etc.). The hydrophobic, powdered lubricant is carried over as a residue on the particles, and it not only retards dissolution of the particles, but also it leaves an objectionable scum or film on the surface of the aqueous solution in which the particles have been dissolved.
The tableting, milling and sieving procedure described above can also be employed on commercially available maltodextrins to eliminate the relatively fine powdered form in which it normally occurs. However, the resulting product has relatively poor dissolution properties and leaves a scum in the dissolving liquid. The commercially available maltodextrin can also be treated by passing the fine powder through two pressurized rolls in a roller-compactor. This forms the powder into a compacted sheet which can then be milled or granulated and sieved to the desired particle size distribution. The drawbacks to this procedure are numerous, however.
One such drawback is that the rolls quickly become warm. The maltodextrin then begins to stick to the rolls which forces a shut down of the equipment. Some of this sticking can be overcome by circulating cooling water through the rolls, but to fully prevent the maltodextrin from sticking to the rolls, a lubricant must be added to the powder. However, this produces the same problems as occur in the tableting procedure when a lubricant is employed to help separate the tablets from the die cavities: there is a carry-over of lubricant onto the resulting particles, and this retards dissolution of the particles and leaves an objectionable scum or film in the dissolving liquid. Another drawback to the roll compacting procedure is that the resulting densified particles can only go into solution by surface erosion, thereby decreasing the rate of solution.